The embodiments herein relate generally to subterranean formation operations and, more particularly, to crosslinkable proppant particulates.
Subterranean wells (e.g., hydrocarbon producing wells, water producing wells, and the like) are often stimulated by hydraulic fracturing treatments. In hydraulic fracturing treatments, a gelled treatment fluid is often pumped into a portion of a subterranean formation at a rate and pressure such that the subterranean formation breaks down and one or more fractures are formed therein. Particulate solids, such as graded sand, are typically suspended in at least a portion of the treatment fluid and deposited into the fractures in the subterranean formation. These particulate solids, or “proppants particulates” (also referred to simply as “proppants”) serve to prop the fracture open (e.g., keep the fracture from fully closing) after the hydraulic pressure is removed. By keeping the fracture from fully closing, the particulates aid in forming conductive paths through which produced fluids, such as hydrocarbons, may flow.
Hydraulic fracturing treatments may also be combined with sand control treatments, such as a gravel packing treatment. Such treatments may be referred to as “frac-packing” treatments. In a typical frac-packing treatment, a gelled treatment fluid comprising a plurality of particulates (e.g. is pumped through the annulus between a wellbore tubular mounted with a screen and a wellbore in a subterranean formation. The fluid is pumped into perforations through a casing, or directly into the wellbore in the case of open hole completions at a rate and pressure sufficient to create or enhance at least one fracture, and the particulates are deposited in the fracture and in the annulus between the screen and the wellbore. The particulates aid in propping open the fracture, as well as controlling the migration of formation fines or other loose particles in the formation from being produced with produced fluids.
The degree of success of a fracturing operation (both a traditional hydraulic fracturing operation and a frac-packing operation) depends, at least in part, upon fracture porosity and conductivity once the fracturing operation is complete and production is begun. Fracturing operations may place a volume of particulates into a fracture to form a “proppant pack” or “gravel pack” (referred to herein as “proppant pack”) in order to ensure that the fracture does not close completely upon removing the hydraulic pressure. In some fracturing operations, a large volume of particulates may be placed within the fracture to form a tight proppant pack. In other fracturing operations, a much reduced volume of particulates may be placed in the fracture to create larger interstitial spaces between the individual particulates. However, both fracturing approaches may result in at least some settling of the particulates within a treatment fluid as the treatment fluid is introduced downhole or after placement in a fracture opening.
Particulate settling may lead to a fracture or a top portion (wherein top refers to the opposite direction of gravity) of a fracture closing, which may lower the conductivity of the proppant fracture and result in proppant masses having little or no interstitial spaces at the bottom portion of a fracture, thereby further decreasing the conductivity of the fracture. Proppant settling may be particularly problematic in cases where larger or heavier are used in place of traditional proppant particulates which may be more difficult to hold in suspension. While settling may be counteracted by using a high pump rate or by increasing the viscosity of the fluid carrying the proppant particulates, such methods often lose effectiveness once the fluid comprising the proppant is placed into a fracture and before the hydraulic pressure is released.